Electric fire alarm



Jan. 28, i GARNER ELECTRIC FIRE ALARM Filed Dec. 15, 1933 fusile eleme122.

Patented Jan. 28, 1936 UNITED STATEfi FATENT OFFICE ELECTRIC FIRE ALARMClaims.

The object of the invention is to provide improvements in switches suchas are used in fire alarm systems, in which the switch automaticallycloses (in normally open-circuit systems) the 5 circuit in order tothereby indicate in well-known manner the location of the blaze, or atleast the excessive heat therefrom.

Another object is to provide a device of this character, which is notonly inexpensive to manufacture, but which comprises but few parts andthose parts so constructed and inter-related as to prevent any tendencyof their becoming broken, loosened or otherwise inoperative, or fail tofunction.

A further object is to provide in such a device a base, which isattachable to and detachable from a supporting wall or ceiling surface,independently of the other parts of the device, together with a casingin which the switch is unitarily mounted, and which casing can bereadily and securely attached to said base after the latter isinstalled, or removed therefrom for the purpose of inspecting the partsof the switch, without in any way altering or affecting the otherconductors, contacts and connections of the circuit.

Still another object is to provide in such a switch, the combination ofa casing having an aperture, the sides or edges of which apertureprovide a seat, a disc of fusible alloy or other suitable material,normally spanning and closing said aperture and resting uniformlyagainst said seat, a switch element secured at one end to said disc andits opposite end portion being operative to span and electricallyconnect two or more contact members, together with a suitable springoperative to actuate and cause said switch element to function instantlyupon the softening or melting of said disc.

And a still further object is to provide in such a device, thecombination of a partition-within said casing having an aperture,surrounded by an integral cylindrical extension, thru which said switchelement extends loosely and slidably, and by means of which said elementis guided towards said contact members, and if desired said casingcomprising a radially restricted portion, the walls of which can be madeto operate as an auxiliary guide for the purpose of controlling thedirection of movement of said element, in the event of said cylindricalextension in anyway becoming broken off or fractured.

With these and other objects in mind, the invention comprises furtherdetails of construction and operation, which are hereinafter fullythreaded disc-like base I, having a suitable number of properlypositioned apertures 2, thru which screws, bolts, or other means, mayextend in order to attach said disc to the ceiling 3, or other suitablewall surface. This disc is preferably formed from plastic material suchas the wellknown bakelite or similar insulating material, and fixedlycarries two or more electrical contact members 4, each of which isprovided with a screw or other suitable means 5, for attaching one ormore wires thereto, while the adjacent end e portions of said membersare directed angularly away from said supporting disc, and thencedivergently in order to provide a pair of contact surfaces 6, saidmembers being also provided with any suitable lug or the like I, whichby being emedded within the body of said disc, serves to rigidly andunitarily secure such member thereto.

The casing for the improved switch comprises an annular upwardlyextending and internally threaded cylindrical portion 8, the walls ofwhich at a position spaced from said disc, when operatively attachedthereto, are directed inwardly at 9, and thence again downwardly, toform a substantially cylindrical section II) of relatively restricteddiameter, and adapted to perform a function hereinafter referred to.Beneath said cylindrical section, said walls are again directedoutwardly at H and thence downwardly to form a cylindrical housing [2,the lower end portion of which is externally threaded, in order todetachably receive the similarly threaded flanged extension 13 of aclosure member M, which latter is provided centrally in its normallydownwardly directed surface with an aperture, bounded by upwardlyconverging surfaces !5. within said housing is a partition is, theradially outer edge portions of which rest upon an annular shoulder llof said closure member, and are secured in fixed binding relationtherewith by the free edge portion N3 of the housing section KPositioned l2 of said casing. This partition in turn is provided with apreferably centrally positioned aperture E9, in alignment with whichprojects an upwardly projecting cylindrical extension 2%].

Normally spanning the area of the aperture in said closure, anduniformly seated upon and with respect to the conical surfaces i5, is asuitably shaped disc of a fusible alloy 2|, having an upper periphery22, which conforms in shape with the seat l5. Embedded within saidfusible disc is the head portion 23 of a rod 24, comprising a switchelement, which extends slidably thru said partition extension 2i and isprovided with a collar 25, having a radially extending flange 26 andsecured against movement upon said element by means of a pin or thelike, while the opposite end of said element has secured to it by meansof a second pin or the like 28 an enlarged circular metallic head 29,having an annular conical contact surface 33, adapted when in thedot-anddash position indicated in Fig. 1 to electrically contact withand span the gap between the contact surfaces 6 of the electricallyconductive members i.

A coil spring or the like St extends between and bears against thepartition i6 and collar flange 26 at its respective opposite ends, whichends surround and are axially positioned by said cylindrical extension2%! and collar 25, the function of this spring being to force saidswitch element 24 normally upwardly, so that the metallic head 29contacts with and electrically con-' nects the electric contact memberst instantly upon the softening or melting of the fusible disc 2 l in thepresence of fire or heat therefrom rising above a predeterminedtemperature, which is predetermined by the composition of the alloy ofsaid fusible disc.

This improved switch may be properly connected in a fire alarm system ofwiring, by extending such wires thru the apertures 32 in the base i orin the event that such wires have to be brought to said switch thru ametal conduit, especially as when the system is installed after abuilding is erected, such conduit of any wellknown form and constructioncan be attached to a boss, such as is represented by the dot-anddashlines 33, forming an integral extension of the upper section 8 of theswitch casing, and in which case an inlet aperture 36 would lead thrusuch boss. It is also to be noted that while there is almost nolikelihood of the partition extension 20 being fractured or broken off,in the event that such might occur, the restricted section it? of saidcasing if of the pro er diameter may serve as an auxiliary guide, eitherfor the switch element 26 direct, or for the collar flange 26, so thatthe head 29 will be directed more or less in a rectilinear path towardsthe conical contact members 6, upon reaching and cooperating with whichsaid head will be automatically seated centrally with respect thereto.

I am aware that the invention may be embodied in other specific formswithout departing from the spirit or essential attributes thereof, and Itherefore desire the present embodiment to be considered in all respectsas illustrative and not restrictive, reference being had to the appendedclaims rather than to the foregoing description to indicate the scope ofthe invention.

Having thus described my invention what I claim as new and desire tosecure by Letters Patent is:

l. A switch for electric fire alarm systems, comprising a casing, a baseadapted to be normally secured to a supporting surface and detachablysupporting said casing, a plurality of electrical contact memberscarried by said base, said casing having an open side, a coverdetachably closing said side and itself having an aperture, a closure offusible material normally spanning said aperture, a switch elementhaving a portion attached to said closure, and resilient means operativeupon the softening of said closure and the release of said element, toforce said element away from said cover and into a position electricallyconnecting said contact members.

2. A switch for electric fire alarm systems, comprising a casing, a baseadapted to be normally secured to a wall or ceiling surface anddetachably support said casing in threaded engagement, a plurality ofelectrical contact members operatively positioned within said casing,said casing having an open side, a cover in threaded engagement with anddetachably closing said side, and itself having an aperture, a fusibleclosure for said aperture, a switch element having an enlarged portionembedded in said closure, and resilient means operative upon thesoftening of said closure and the release of said element, to force saidelement into a position electrically connecting said contact members.

3. A switch for electric fire alarm systems, comprising a casing, a baseadapted to be normally secured to a wall or ceiling surface anddetachably support in threaded engagement said casing, a plurality ofelectrical contact members operatively positioned within said casing,said casing having an open side, a cover having an annular shoulder andin threaded engagement with said casing, said cover itself having anaperture, a fusible closure for said aperture, a removable partitionresting upon said shoulder and maintained thereby by said casing, saidpartition having an aperture, and a switch element having an enlargedportion embedded in said closure and extending slidably thru saidpartition aperture, and a spring extending between and engaging saidpartition and a portion of said element, whereby upon the softening ofsaid closure said element will be automatically shifted so as toelectrically connect with said contact members.

4. A switch for electric fire alarm systems, comprising a casing, a baseadapted to be normally secured to a wall or ceiling surface anddetachably support in threaded engagement said casing, a plurality ofelectrical contact members operatively positioned within said casing,said casing having'an open side, a cover having an annular shoulder andin threaded engagement with said casing, said cover itself having anaperture, a fusible closure for said aperture, a removable partitionresting upon said shoulder and maintained thereby by said casing, saidpartition having an aperture, and a cylindrical projection extendingaxially with respect to said lastmentioned aperture, and a switchelement having an enlarged portion embedded in said closure, a head uponits opposite end and extending slidably thru said cylindrical projectionas a guide, and a coil spring surrounding said projection and saidswitch element between said partition and said head, whereby upon thesoftening of said closure said element will be automatically shifted soas to electrically connect said contact members.

5. A switch for electric fire alarm systems,

comprising a casing, a base adapted to be normally secured to a wall orceiling surface and detachably support in threaded engagement saidcasing, a plurality of electrical contact members operatively positionedwithin said casing, said casing having an open side, a cover having anannular shoulder and in threaded engagement with said casing, said coveritself having an aperture, a fusible closure for said aperture, aremovable partition resting upon said shoulder and maintained thereby bysaid casing, said partition having an aperture, a cylindrical projectionextending axially with respect to said lastmentioned aperture, saidcasing having a radialso as to electrically connect said contactmembers.

JOSEPH GARNER.

